Westminster attack: Families and survivors joined by William, Kate and Harry at service

A woman whose husband was killed in front of her during the Westminster terror attack joined families of other victims at a service to pay tribute to those who lost their lives.

Arriving in a wheelchair after suffering a broken leg and rib in the atrocity, American tourist Melissa Cochran smiled as she was pushed into Westminster Abbey on Wednesday.

She had been in London celebrating her 25th wedding anniversary with husband Kurt when a car driven by terrorist Khalid Masood ploughed into crowds on Westminster Bridge two weeks ago.

Mr Cochran was one of four people killed in the tragedy.

The Service of Hope to remember the victims was attended by 1,800 people of different nationalities and faiths, including the Duke and Duchess of Cambridge and Prince Harry.

Rows of police officers and medics marked the loss of the victims: mother-of-two Aysha Frade, retired window cleaner Leslie Rhodes, Mr Cochran and PC Keith Palmer, who was stabbed to death on the cobbles outside the Palace of Westminster by Masood.

The Royals spoke to the families of those killed in the attack, as well as survivors and first responders, many from the Metropolitan Police.

Prince William read the story of the Good Samaritan, and laid a wreath of spring flowers, including red and white roses and gerbera, at the Innocent Victims memorial outside the abbey.

A card on the wreath read: "In memory of the innocent lives; lost to us all on the 22nd March, 2017."

:: Timeline of terror

Home Secretary Amber Rudd also gave a reading, and sat alongside the incoming Metropolitan Police Commissioner Cressida Dick and London Mayor Sadiq Khan.

Also attending were Labour leader Jeremy Corbyn and House of Commons Speaker John Bercow.

Absent from the service was Policing Minister Brandon Lewis, who had been invited, and whose private office said he had been on annual leave.

However, a Home Office spokesman later clarified that Mr Lewis was not on annual leave, or holiday, but confirmed he had not been at the service, saying the Home Secretary had been there to represent the department.

The Dean of Westminster, the Very Rev John Hall, who led the service, told the congregation: "What happened a fortnight ago leaves us bewildered.

"What could possibly motivate a man to hire a car and take it from Birmingham to Brighton to London, and then drive it fast at people he had never met, couldn't possibly know, against whom he had no personal grudge, no reason to hate them and then run at the gates of the Palace of Westminster to cause another death?

"It seems likely that we shall never know.

"No doubt it was in imitation of the attacks in Nice and Berlin. But what on earth did he hope to achieve? Such random acts of aggression are nothing new."

But he said that despite the "random killing and hatred shown two weeks ago" there was much to offer hope.

In the wake of the attacks, he said, Londoners and leaders of all faiths have joined together to condemn the violence.

As everyone in the congregation lit a candle, representatives from different faiths read prayers, including Rabbi Baroness Julia Neuberger and Mr Khan.

Among the congregation was Red Cross senior emergency response officer Alex Hurrell, who helped hundreds of survivors taken to the abbey for refuge after the attack.

He said: "The service was a very good and thoughtful way of remembering what happened and the people that have been most directly affected by it."

Parliamentary staff caught up in the horrors of the day also attended the service.

Perhaps most striking were the scores of police officers from all over the country who had come to the abbey as a mark of respect for PC Palmer, who died in the line of duty.

His funeral will be held on Monday, when thousands more officers will line the streets.